Copolymer, polymer, molding material and resin molded body

ABSTRACT

The present invention provides: a copolymer (A) which is a copolymer obtained by copolymerizing one or plural cycloolefin monomers and one or plural acyclic olefin monomers, or by copolymerizing two or more cycloolefin monomers, wherein a glass transition temperature (Tg) is 100° C. or higher, a refractive index is 1.545 or higher, and an Abbe&#39;s number is 50 or larger; a polymer (B) selected from: a ring-opening homopolymer obtained by ring-opening polymerization of only a monomer represented by formula (I), a ring-opening copolymer obtained by ring-opening copolymerization of the monomer represented by formula (I) and a monomer capable of ring-opening copolymerization with the monomer represented by formula (I), a hydrogenated product of the ring-opening homopolymer and a hydrogenated product of the ring-opening copolymer; a forming material containing the copolymer (A) or the polymer (B); and a resin formed article obtained by forming the forming material.

TECHNICAL FIELD

The present invention relates to a novel copolymer having a high glasstransition temperature (Tg), a high refractive index and a high Abbe'snumber, a forming material containing the copolymer, and a resin formedarticle obtained by forming the forming material. In addition, thepresent invention relates to a polymer useful as a resin component of anoptical formed article, a forming material containing the polymer, and aresin formed article obtained by forming the forming material.

BACKGROUND ART

Since polymers having repeating units derived from a cycloolefin monomerare excellent in transparency, low hygroscopicity, heat resistance,insulation property, chemical resistance and the like, they have beenbroadly utilized as forming materials for optical members and the likesuch as optical lenses.

For example, Patent Literature 1 describes an addition copolymer of anorbornene-based monomer and ethylene. Further, this literature alsodiscloses a copolymer of 1,4-methano-1,4,4a-9a-tetrahydrofluorene (MTF)and ethylene in Examples. This copolymer has a high glass transitiontemperature (Tg) and a high refractive index, and is useful as a resincomponent of an optical formed article.

In addition, the resin component of the optical formed article such as alens requires excellent transparency. From this viewpoint, poly(methylmethacrylate), polycarbonate, diethylene glycol bisallyl carbonate,poly(cyclohexyl methacrylate), poly(4-methylpentene), amorphousalicyclic polyolefin, polycyclic norbornene polymer, a vinyl alicyclichydrocarbon polymer and the like have conventionally been used as resincomponents of optical formed articles. For example, Patent Literature 2describes an optical formed article obtained by using a forming materialcontaining a polycyclic norbornene polymer having a specific repeatingunit.

In recent years, lenses for mobile phone cameras and the like arerequired to be further thinner and to have enhanced resolution. Thus, aresin having not only excellent transparency but also high refractiveindex and low birefringence has been required.

CITATION LIST Patent Literature

Patent Literature 1: JP-A-2008-144013

Patent Literature 2: JP-A-2008-174679

SUMMARY OF INVENTION Technical Problem

By using a cycloolefin monomer having an aromatic ring such as MTF likethe copolymer described in Patent Literature 1, a polymer having a highglass transition temperature and a high refractive index can be easilyobtained. However, since a polymer having an aromatic ring in itsmolecule tends to have a lower Abbe's number, a polymer having a highglass transition temperature (Tg), a high refractive index and a highAbbe's number was hardly obtained by introducing an aromatic ring.

The present invention was achieved in view of the above circumstances,and the first object of the present invention is to provide a novelcopolymer having a high glass transition temperature (Tg), a highrefractive index and a high Abbe's number, which is useful as a resincomponent of an optical formed article, a forming material containingthe copolymer, and a resin formed article obtained by forming theforming material.

In addition, the second object of the present invention is to provide apolymer useful as a resin component of an optical formed article, aforming material containing the polymer, and a resin formed articleobtained by forming the forming material.

Solution to Problem

In order to solve the above problem, the inventors conducted extensivestudies with regard to a polymer having a repeating unit derived from acycloolefin monomer. As a result, the inventors have found that acopolymer having a high glass transition temperature (Tg), a highrefractive index and a high Abbe's number can be obtained bycopolymerizing a cycloolefin monomer appropriately in combination withan acyclic olefin monomer or by copolymerizing two or more cycloolefinmonomers appropriately in combination, and that a resin having excellenttransparency, and furthermore a high refractive index and a lowbirefringence can be obtained by using a monomer represented by formula(I) described below as a cycloolefin monomer. These findings have led tothe completion of the present invention.

Thus, one aspect of the invention provides a copolymer (A) of [1] to[7], a polymer (B) of [7] to [13] , a forming material of [14] and [15], and a resin formed article of [16] described below.

[1] A copolymer (A), which is a copolymer obtained by copolymerizing oneor plural cycloolefin monomers and one or plural acyclic olefinmonomers, or a copolymer obtained by copolymerizing two or morecycloolefin monomers,

wherein a glass transition temperature (Tg) is 100° C. or higher, arefractive index is 1.545 or higher, and an Abbe's number is 50 orlarger.

[2] The copolymer (A) according to [1], wherein a ratio of the number ofcarbon atoms to the number of hydrogen atoms (number of carbonatoms/number of hydrogen atoms) in at least one of the cycloolefinmonomers is 0.65 to 1.00.

[3] The copolymer (A) according to [1] or [2], wherein at least one ofthe cycloolefin monomers is a norbornene-based monomer.

[4] The copolymer (A) according to any one of [1] to [3], wherein atleast one of the cycloolefin monomers is a deltacyclene.

[5] The copolymer (A) according to any one of [1] to [4], wherein atleast one of the cycloolefin monomers is a monomer represented by thefollowing formula (I).

[6] The copolymer (A) according to any one of [1] to [5], wherein atleast one of the acyclic olefin monomers is an α-olefin-based monomerhaving 2 to 18 carbon atoms.

[7] The copolymer (A) according to any one of [1] to [6], wherein atleast one of the acyclic olefin monomers is ethylene.

[8] A polymer (B) selected from: a ring-opening homopolymer obtained byring-opening polymerization of only a monomer represented by thefollowing formula (I);

a ring-opening copolymer obtained by ring-opening copolymerization ofthe monomer represented by the above formula (I) and a monomer capableof ring-opening copolymerization with the monomer represented by theabove formula (I); a hydrogenated product of the ring-openinghomopolymer; and a hydrogenated product of the ring-opening copolymer.

[9] The polymer (B) according to [8], wherein the monomer capable ofring-opening copolymerization with the monomer represented by the aboveformula (I) is a compound represented by the following formula (II).

[10] The polymer (B) according to [8] or [9], wherein a refractive index(n_(d)) is 1.540 or higher.

[11] The polymer (B) according to any one of [8] to [10], wherein abirefringence (δn) per a unit thickness is −100 to +100.

[12] The polymer (B) according to any one of [8] to [11], wherein nomelting point is observed, when a measurement sample obtained by meltingand subsequent cooling is subjected to DSC measurement while heating itto 350° C. at an increase rate of 10° C./min.

[13] The polymer (B) according to any one of [8] to [12], wherein aglass transition temperature is 120 to 180° C.

[14] A forming material containing the copolymer (A) according to anyone of [1] to [7] or the polymer (B) according to any one of [8] to[13].

[15] The forming material according to [14], wherein no melting point isobserved when carrying out DSC measurement.

[16] A resin formed article obtained by forming the forming materialaccording to [14] or [15].

Advantageous Effects of Invention

One aspect of the invention provides a novel copolymer [A] having a highglass transition temperature (Tg), a high refractive index and a highAbbe's number, which is useful as a resin component of an optical formedarticle, a forming material containing the copolymer [A], and a resinformed article obtained by forming the forming material.

In addition, one aspect of the invention provides a polymer [B] usefulas a resin component of an optical formed article, a forming materialcontaining the polymer [B], and a resin formed article obtained byforming the forming material.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a ¹H-NMR chart (without integral representation) of amonomer (5). The abscissa represents values of chemical shift (ppm), andthe ordinate represents peak intensities.

FIG. 2 illustrates a ¹H-NMR chart (with integral representation) of themonomer (5). The abscissa represents values of chemical shift (ppm) andthe ordinate represents peak intensities.

FIG. 3 illustrates a GC chart of the monomer (5). The abscissarepresents time (min), and the ordinate represents peak intensities.

FIG. 4 illustrates a ¹H-NMR chart (without integral representation) of amonomer (6). The abscissa represents values of chemical shift (ppm), andthe ordinate represents peak intensities.

FIG. 5 illustrates a ¹H-NMR chart (with integral representation) of themonomer (6). The abscissa represents values of chemical shift (ppm), andthe ordinate represents peak intensities.

FIG. 6 illustrates a GC chart of the monomer (6). The abscissarepresents time (min), and the ordinate represents peak intensities.

DESCRIPTION OF EMBODIMENTS

Hereinafter, the present invention is classified into 1) copolymer (A),2) polymer (B), 3) forming material and 4) resin formed article, anddescribed in detail.

1) Copolymer (A)

The copolymer (A) according to one embodiment of the invention is acopolymer obtained by copolymerizing one or plural cycloolefin monomersand one or plural acyclic olefin monomers or a copolymer obtained bycopolymerizing two or more cycloolefin monomers, wherein a glasstransition temperature (Tg) is 100° C. or higher, a refractive index is1.545 or higher, and an Abbe's number is 50 or larger.

Hereinafter, among the copolymers (A) according to one embodiment of theinvention, the copolymer obtained by copolymerizing one or pluralcycloolefin monomers and one or plural acyclic olefin monomers isreferred to as “copolymer (AI) ”, and the copolymer obtained bycopolymerizing two or more cycloolefin monomers is referred to as“copolymer (AII)” in some cases.

[Monomer]

The cycloolefin monomer used for producing the copolymer (AI) or thecopolymer (AII) is a compound having a ring structure composed of carbonatoms and including carbon-carbon double bonds on the ring.Specifically, it is exemplified by a monocyclic cycloolefin monomer anda norbornene-based monomer.

Examples of the monocyclic cycloolefin monomer include a cyclicmonoolefin such as cyclobutene, cyclopentene, methylcyclopentene,cyclohexene, methylcyclohexene, cycloheptene and cyclooctene; a cyclicdiolefin such as cyclohexadiene, methylcyclohexadiene, cyclooctadiene,methylcyclooctadiene and phenylcyclooctadiene; and the like.

The term “norbornene-based monomer” refers to a monomer which includes anorbornene ring.

Examples of the norbornene-based monomer include a bicyclic monomer suchas bicyclo[2.2.1]hept-2-ene (trivial name: norbornene),5-ethylidene-bicyclo[2.2.1]hept-2-ene (trivial name:ethylidenenorbornene) and a derivative thereof (which includes asubstituent on the ring); a tricyclic monomer such astricyclo[4.3.0.1^(2,5)]deca-3,7-diene (trivial name: dicyclopentadiene)and a derivative thereof; a tetracyclic monomer such as7,8-benzotricyclo[4.3.0.1^(2,5)]deca-3-ene (trivial name:methanotetrahydrofluorene, also referred to as“tetracyclo[7.4.0.0^(2,7).1^(10,13)]trideca-2,4,6,11-tetraene),tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodeca-3-ene (trivial name:tetracyclododecene),8-ethylidenetetracyclo[4.4.0.1^(2,5).1^(7,10)]-3-dodecene and aderivative thereof; a monomer having not less than 5 rings such as1,2,3,3a,4,6a-hexahydro-1,2,4-methenopentalene (trivial name:deltacyclene),1,2,3,3a,3b,4,7,7a,8,8a-decahydro-4,7-methano-2,3,8-methenocyclopent[a]indene (the monomer represented by the above formula (I),hereinafter referred to as “MMD” in some cases) and a derivativethereof; and the like.

The MMD can be synthesized by reactions represented by e.g. thefollowing formulas (α) and (β).

The reaction represented by the formula (α) (hereinafter, this reactionis referred to as “reaction (α)” in some cases) is a general Diels-Alderreaction, for which known reaction conditions can be utilized. Inaddition, the reaction represented by the formula (β) (hereinafter, thisreaction is referred to as “reaction (β)” in some cases) can be carriedout in accordance with a method described in Polymer Bulletin 18,203-207 (1987), Journal of Catalyst 258, 5-13 (2008), J. Am. Chem. Soc.1972, 94, 5446 or the like.

Specifically, the MMD can be synthesized by the reaction (α) or thereaction (β) when the reaction is carried out at 0 to 300° C. in thepresence or absence of a solvent. At this time, a catalyst may be usedas required.

Examples of the solvent include an aromatic hydrocarbon-based solventsuch as benzene, toluene and xylene; an aliphatic hydrocarbon-basedsolvent such as pentane and hexane; an alicyclic hydrocarbon-basedsolvent such as cyclohexane and methylcyclohexane; an alcohol-basedsolvent such as methanol, ethanol, isopropanol and butanol; anether-based solvent such as tetrahydrofuran, diethyl ether, dipropylether and 1,4-dioxane; an ester-based solvent such as ethyl acetate andpropyl acetate; a halogen-containing compound-based solvent such asmethylene chloride and chloroform; a nitrogen-containing compound-basedsolvent such as N-methylpyrrolidone; and the like.

The MMD includes 4 stereoisomers represented by the following formulas.

It is known that when the MMD is synthesized by the reaction (α), anendo-adduct (an endo-endo product or an endo-exo product) ispreferentially produced by kinetic control (referred to as an endorule).

When MMD is synthesized by the reaction (β), it is known that the ratioof the produced isomer varies depending on the reaction conditions. Forexample, there are reports that an exo-endo product is preferentiallyproduced under the condition described in J. Am. Chem. Soc. 1972, 94,5446, J. Mol. Catal. A. 1996, 106, 159, and that an endo-endo product ispreferentially produced under the condition described in New. J. Chem.1996, 20, 677.

Thus, although some of the norbornene-based monomers includestereoisomers, all of these stereoisomers can be used as monomers in thepresent invention. In addition, as a monomer, one isomer may be usedalone, or alternatively an isomer mixture including two or more isomersin an arbitrary ratio may be used.

The above-described norbornene-based monomer may have a substituent atan arbitrary position. Examples of such a substituent include an alkylgroup such as a methyl group and an ethyl group; an alkenyl group suchas a vinyl group; an alkylidene group such as an ethylidene group and apropane-2-ylidene group; an aryl group such as a phenyl group; a hydroxygroup; an acid anhydride group; a carboxyl group; an alkoxycarbonylgroup such as a methoxycarbonyl group; and the like.

These cycloolefin monomers may be used either alone or in combination.

A ratio of the number of carbon atoms to the number of hydrogen atoms(number of carbon atoms/number of hydrogen atoms) in at least one of thecycloolefin monomers to be used is preferably 0.65 to 1.00, morepreferably 0.66 to 0.95, and even more preferably 0.67 to 0.90. If theratio is too low, the refractive index possibly decreases. On the otherhand, if the ratio is too high, the Abbe's number (ν_(d)) possiblydecreases.

The cycloolefin monomer satisfying the above ratio is preferably anorbornene-based monomer, more preferably a monomer having 5 or morerings, and even more preferably a deltacyclene or an MMD, because apolymer having a high glass transition temperature (Tg), a highrefractive index and a high Abbe's number can be easily obtained.

The acyclic olefin monomer used for producing the copolymer (AI) is acompound having a polymerizable carbon-carbon double bond in itsmolecule (with the proviso of excluding cycloolefin monomers). Theacyclic olefin monomer maybe linear or branched, or may have a ringstructure. Further, the acyclic olefin monomer may be an α-olefin or aninternal olefin.

The acyclic olefin monomer can be used either alone or in combination.

At least one of the acyclic olefins to be used is preferably anα-olefin-based monomer having 2 to 18 carbon atoms, and more preferably2 to 10 carbon atoms.

Examples of such an α-olefin monomer include ethylene; α-olefin such aspropylene, 1-butene, isobutene, 1-pentene, 3-methyl-1-butene, 1-hexene,4-methyl-1-pentene, 3-methyl-1-pentene, 1-octene, 1-decene, 1-dodecene,1-tetradecene, 1-hexadecene, 1-octadecene, 2-vinylnorbornane,3-vinyltetracyclo[4.4.0.1^(2,5).1^(7,10)]dodecane; and the like. Aboveall, ethylene is preferred.

[Copolymer (A)]

A copolymer (A) according to one embodiment of the invention is acopolymer obtained by copolymerizing one or plural cycloolefin monomersand one or plural acyclic olefin monomers or a copolymer obtained bycopolymerizing two or more cycloolefin monomers, wherein a glasstransition temperature (Tg) is 100° C. or higher, a refractive index is1.545 or higher, and an Abbe's number is 50 or larger.

The copolymer (A) according to one embodiment of the invention isnormally a polymer having an alicyclic structure in its molecule.

Examples of the alicyclic structure contained in the copolymer (A)according to one embodiment of the invention include a cycloalkanestructure and a cycloalkene structure. Above all, a cycloalkanestructure is preferred because a copolymer excellent in transparency,light resistance, durability and the like can be easily obtained. Thenumber of carbon atoms constituting the alicyclic structure is notparticularly limited, but is normally 4 to 30, preferably 5 to 20, andmore preferably 5 to 15.

The weight average molecular weight (Mw) of the copolymer (A) accordingto one embodiment of the invention is preferably 10,000 to 300,000, andmore preferably 20,000 to 200,000. A strength of a resin formed articleobtained by using a copolymer having a low weight average molecularweight (Mw) possibly decreases. On the other hand, if the weight averagemolecular weight (Mw) of the copolymer (A) is too high, the formabilityof the forming material possibly decreases.

The molecular weight distribution (Mw/Mn) of the copolymer (A) accordingto one embodiment of the invention is not particularly limited, but ispreferably 1 to 8, and more preferably 1 to 6.

When the molecular weight distribution of the copolymer (A) is withinthe above range, a resin formed article having a sufficient mechanicalstrength can be obtained.

The weight average molecular weight (Mw) and the number averagemolecular weight (Mn) of the copolymer (A) refer to standardpolyisoprene-equivalent values determined by gel permeationchromatography (GPC) using cyclohexane as an eluent.

The copolymer (A) according to one embodiment of the invention ispreferably a copolymer having a repeating unit derived from acycloolefin monomer satisfying the ratio of the number of carbon atomsto the number of hydrogen atoms described above.

When the copolymer (A) according to one embodiment of the invention isthe copolymer having the repeating unit derived from the cycloolefinmonomer satisfying the ratio of the number of carbon atoms to the numberof hydrogen atoms described above, the amount of such a repeating unitis preferably 60 wt % or more, more preferably 65 wt % or more, and evenmore preferably 70 wt % or more based on the whole repeating unit.

Among the copolymers (A) according to one embodiment of the invention,examples of the copolymer (AI) include a polymer obtained by additioncopolymerization of one or plural of the cycloolefin monomers and one orplural of the acyclic olefin monomers, or a hydrogenated product hereof.

The copolymer (AI) may contain one or plural repeating units derivedfrom a cycloolefin monomer. Further, it may contain one or pluralrepeating units derived from an acyclic olefin monomer.

The copolymer (AI) may be a block copolymer or a random copolymer.

The weight ratio of the repeating unit derived from the cycloolefinmonomer to the repeating unit derived from the acyclic olefin monomer(repeating unit derived from the cycloolefin monomer:repeating unitderived from the acyclic olefin monomer) in the copolymer (AI) ispreferably 85:15 to 15:85, and more preferably 70:30 to 30:70.

The method for producing the copolymer (AI) is not particularly limited.For example, the copolymer (AI) can be produced by a radicalpolymerization reaction, an anionic polymerization reaction, a cationicpolymerization reaction, a coordination polymerization reaction or thelike. Above all, the coordination polymerization reaction is preferredbecause the target addition copolymer can be obtained with a high yield.

The details of the reaction conditions in the coordinationpolymerization reaction are not particularly limited, and aconventionally known method can be appropriately utilized.

For example, the copolymer (AI) can be produced by polymerizing acycloolefin monomer and an acyclic olefin monomer using a polymerizationcatalyst.

As the polymerization catalyst in the coordination polymerizationreaction, a known polymerization catalyst for an addition polymerizationreaction can be used. Examples of such a polymerization catalyst includea metallocene catalyst including a metallocene compound (a) containing aGroup 4 metal atom, and an organoaluminumoxy compound (b), for example.

Examples of the metallocene compound (a) include a crosslinkedmetallocene compound, a half metallocene compound and a non-crosslinkedhalf metallocene compound.

Examples of the crosslinked metallocene compound include, for example, acompound represented by the following formula (III).

In the formula (III), M₁ is a metal atom selected from a groupconsisting of titanium, zirconium and hafnium, where zirconium ispreferred because of excellent catalytic activity.

Each of X₁ and X₂ independently represents an alkyl group having 1 to 6carbon atoms or a halogen atom.

R₁ represents a divalent group. Examples of R₁ include an alkylene grouphaving 1 to 5 carbon atoms such as a methylene group, an ethylene group,a trimethylene group and a propane-2,2-diyl group (isopropylidenegroup); a group having 1 to 5 silicon atoms such as silylene group and adisilylene group; and the like. They may have a substituent. Examples ofR₁ having a substituent include a diphenylmethylene group, adimethylsilylene group, a diphenylsilylene group, and the like.

Each of R₂ and R₃ independently represents a cyclopentadienyl group, anindenyl group or a fluorenyl group. These groups may have a substituentat an arbitrary position. Examples of such a substituent include analkyl group having 1 to 10 carbon atoms such as a methyl group, an ethylgroup, an isopropyl group and a t-butyl group; an aryl group having 6 to12 carbon atoms such as a phenyl group; an arylalkyl group such as abenzyl group and a phenethyl group; and the like.

Examples of the compound represented by formula (III) includeisopropylidene-(9-fluorenyl) (cyclopentadienyl) zirconium dichloride,isopropylidene-(9-fluorenyl)[1-(3-methyl)cyclopentadienyl] zirconiumdichloride, isopropylidene-(9-fluorenyl)[1-(3-t-butyl)cyclopentadienyl]zirconium dichloride, isopropylidene-(1-indenyl)(cyclopentadienyl)zirconium dichloride,isopropylidene-bis(1-indenyl)zirconium dichloride,diphenylmethylene-(9-fluorenyl) (cyclopentadienyl)zirconium dichloride,diphenylmethylene-bis(1-indenyl)zirconium dichloride,ethylene-bis(1-indenyl)zirconium dichloride, dimethylsilylene-bis(1-indenyl) zirconium dichloride, and the like.

Examples of the half metallocene compound include, for example, acompound represented by the following formula (IV).

In the formula (IV), M₂ is a metal atom selected from a group consistingof titanium, zirconium and hafnium, where zirconium is preferred becauseof excellent catalytic activity.

Each of X₃ and X₄ independently represents an alkyl group having 1 to 6carbon atoms, or a halogen atom.

R₄ represents a divalent group. Examples of R₄ include the same groupsas those indicated for R₁.

R₅ represents a cyclopentadienyl group, an indenyl group, or a fluorenylgroup. These groups may have a substituent at an arbitrary position.Examples of such a substituent include an alkyl group having 1 to 10carbon atoms such as a methyl group, an ethyl group, an isopropyl groupand a t-butyl group; an aryl group having 6 to 12 carbon atoms such as aphenyl group; an arylalkyl group such as a benzyl group and a phenethylgroup; and the like.

R₆ represents an alkyl group having 1 to 6 carbon atoms.

Examples of the compound represented by formula (IV) include(t-butyramide)dimethyl-1-indenyl silane titanium dimethyl,(t-butyramide)dimethyl-1-indenyl silane titanium dichloride,(t-butyramide)dimethyl-9-fluorenyl silane titanium dimethyl,(t-butyramide)dimethyl-9-fluorenyl silane titanium dichloride,(t-butyramide)dimethyl-9-(3,6-dimethylfluorenyl)silane titaniumdimethyl, (t-butyramide)dimethyl-9-[3,6-di(isopropyl)fluorenyl]silanetitanium dimethyl,(t-butyramide)dimethyl-9-[3,6-di(t-butyl)fluorenyl]silane titaniumdimethyl, (t-butyramide)dimethyl-9-[2,7-di(t-butyl)fluorenyl]silanetitanium dimethyl,(t-butyramide)dimethyl-9-(2,3,6,7-tetramethylfluorenyl) silane titaniumdimethyl, and the like.

Examples of the non-crosslinked half metallocene compound include, forexample, a compound represented by the following formula (V).

In the formula (V), M₃ is a metal atom selected from a group consistingof titanium, zirconium and hafnium, where zirconium is preferred becauseof excellent catalytic activity.

Each of X₅ and X₆ independently represents an alkyl group having 1 to 6carbon atoms or a halogen atom.

R₇ represents a cyclopentadienyl group, an indenyl group or a fluorenylgroup. These groups may have a substituent at an arbitrary position.Examples of such a substituent include an alkyl group having 1 to 10carbon atoms such as a methyl group, an ethyl group, an isopropyl groupand a t-butyl group; an aryl group having 6 to 12 carbon atoms such as aphenyl group; an arylalkyl group such as a benzyl group and a phenethylgroup; and the like.

Each of R₈ and R₉ independently represents an alkyl group having 1 to 6carbon atoms.

Examples of the compound represented by formula (V) includeCpTi[N═C(t-Bu)₂]Cl₂, (t-BuCp)Ti[N═C(t-Bu)₂]Cl₂, CpTi[N═C(t-Bu)₂](CH₃)₂,(t-BuCp)Ti[N═C(t-Bu)₂](CH₃)₂ and the like. In these formulas, “Cp”represents a group represented by R₆.

Above all, the compound represented by the above formula (V) ispreferred as the metallocene compound (a) because of efficientcopolymerization reaction.

The organoaluminumoxy compound (b) constituting the polymerizationcatalyst is an activator for activating the metallocene compound (a).

The organoaluminumoxy compound (b) may be a conventionally knownaluminoxane or a benzene-insoluble organoaluminumoxy compound asdisclosed in JP-A-2-78687.

The polymerization catalyst may contain an organoaluminum compound (c).The organoaluminum compound (c) is an organoaluminum compound other thanthe aluminumoxy compound (b). Examples of such an organoaluminumcompound include a trialkylaluminum such as trimethylaluminum,triethylaluminum, triisopropylaluminum, tri-n-butylaluminum,triisobutylaluminum and tri-sec-butylaluminum; a dialkylaluminum halidesuch as dimethylaluminum chloride and diisobutylaluminum chloride; adialkylaluminum hydride such as diisobutylaluminum hydride; adialkylaluminum alkoxide such as dimethylaluminum methoxide; adialkylaluminum aryloxide such as diethylaluminum phenoxide; and thelike.

The concentration of the metallocene compound (a) at the start of thepolymerization reaction is preferably 0.00005 to 1.0 mmol/L, and morepreferably 0.0001 to 0.3 mmol/L. In addition, the amount of theorganoaluminumoxy compound (b) is preferably 1 to 10,000 equivalentsbased on the metallocene compound (a). When the polymerization catalystcontains the organoaluminum compound (c), the amount of theorganoaluminum compound (c) is preferably 0.1 to 1,000 equivalents basedon the metallocene compound (a).

The polymerization reaction is normally effected in an organic solvent.The organic solvent is not particularly limited as long as it is inertto the polymerization reaction. Examples of the organic solvent to beused include an aromatic hydrocarbon-based solvent such as benzene,toluene and xylene; an aliphatic hydrocarbon-based solvent such asn-pentane, n-hexane and n-heptane; an alicyclic hydrocarbon-basedsolvent such as cyclohexane, methylcyclohexane, decalin andbicyclononane; a halogenated hydrocarbon-based solvent such asdichloroethane, chlorobenzene, dichlorobenzene and trichlorobenzene; andthe like.

The polymerization temperature is normally −50 to 250° C., preferably−30 to 200° C., and more preferably −20 to 150° C. The polymerizationtime is appropriately selected depending on polymerization conditions,but is normally 30 minutes to 20 hours, and preferably 1 to 10 hours.

After the polymerization reaction, the addition copolymer according toone embodiment of the invention can be obtained by carrying outisolation and purification in accordance with an ordinary method.

By hydrogenation reaction of the copolymer obtained by theabove-described method, the hydrogenated product thereof can beobtained.

This hydrogenation reaction can be effected by bringing the copolymerinto contact with hydrogen under the presence of a hydrogenationcatalyst in accordance with an ordinary method.

The hydrogenation catalyst may be a homogeneous catalyst or aheterogeneous catalyst.

Since a homogeneous catalyst is easily dispersed in a hydrogenationreaction solution, the amount of catalyst to be added can be reduced. Inaddition, since a homogeneous catalyst exhibits sufficient activity evenwhen the temperature and the pressure are not increased, decompositionor gelation of the copolymer and a hydrogenated product thereof hardlyoccurs. Therefore, a homogeneous catalyst is preferably used from theviewpoint of cost and the quality of the product.

On the other hand, since a heterogeneous catalyst exhibits particularlyexcellent activity at a high temperature under a high pressure, thecopolymer can be hydrogenated within a short time. Moreover, a catalystresidue can be efficiently removed after completion of the hydrogenationreaction.

Examples of the homogeneous catalyst include a Wilkinson's complex[chlorotris(triphenylphosphine)rhodium(I)]; a catalyst including acombination of a transition metal compound and an alkylmetal compound,such as combinations of cobalt acetate/triethylaluminum, nickelacetylacetonate/triisobutylaluminum, titanocenedichloride/n-butyllithium, zirconocene dichloride/sec-butyllithium,tetrabutoxytitanate/dimethylmagnesium and the like; and the like.

Examples of the heterogeneous catalyst include a catalyst in which ametal such as Ni, Pd, Pt, Ru and Rh is supported on a support.Particularly, when the amount of impurities in the resultinghydrogenated product is to be reduced, it is preferable to use anadsorbent such as alumina and diatomaceous earth as the support.

The hydrogenation reaction is normally effected in an organic solvent.The organic solvent is not particularly limited as long as it is inertto the hydrogenation reaction. As the organic solvent, ahydrocarbon-based solvent is normally used since it can easily dissolvethe resulting hydrogenated product. Examples of the hydrocarbon-basedsolvent include an aromatic hydrocarbon-based solvent such as benzene,toluene and xylene; an aliphatic hydrocarbon-based solvent such asn-pentane, n-hexane and n-heptane; an alicyclic hydrocarbon-basedsolvent such as cyclohexane, methylcyclohexane, decalin andbicyclononane; and the like.

These organic solvents may be used either alone or in combination. Inaddition, a solvent used for a ring-opening polymerization reaction isnormally also suitable as a solvent for a hydrogenation reaction, andtherefore, after the hydrogenation catalyst is added to the ring-openingpolymerization reaction solution, it can be subjected to thehydrogenation reaction.

The hydrogenation ratio varies depending on the type of hydrogenationcatalyst and the reaction temperature. Therefore, when the copolymer hasan aromatic ring, a residual ratio of the aromatic ring can becontrolled by selection of the hydrogenation catalyst, adjustment of thereaction temperature or the like. For example, the unsaturated bonds ofan aromatic ring can be allowed to remain to a certain extent or higherby controls such as decrease of the reaction temperature, lowering ofthe hydrogen pressure and reduction of the reaction time.

A catalyst residue can be removed by a treatment such as centrifugationand filtration after completion of the hydrogenation reaction. Inaddition, a catalyst deactivation agent such as water and alcohol may beused, or an adsorbent such as activated clay and alumina may be added,as required.

Among the copolymers (A) according to one embodiment of the invention,examples of the copolymer (AII) include a polymer obtained by additioncopolymerization of two or more cycloolefin monomers (hereinafterreferred to as “copolymer (AII-a)” in some cases) or a hydrogenatedproduct thereof, and a polymer obtained by ring-opening copolymerizationof two or more cycloolefin monomers (hereinafter referred to as“copolymer (AII-b)” in some cases) or a hydrogenated product thereof.

The copolymer (AII) may be either a block copolymer or a randomcopolymer.

The method for producing the copolymer (AII) is not particularlylimited. For example, the copolymer (AII-a) can be produced by the samemethod as for producing the copolymer (AI) except that two or morecycloolefin monomers are used in combination instead of the combinationof the cycloolefin monomer and the acyclic olefin monomer in the methoddescribed above as a method for producing the copolymer (AI).

In addition, the copolymer (AII-b) can be produced by ring-openingpolymerization of two or more cycloolefin monomers in accordance with aknown method using a metathesis polymerization catalyst.

The metathesis polymerization catalyst is not particularly limited. Aknown metathesis polymerization catalyst may be used. Examples of themetathesis polymerization catalyst include a catalyst system whichincludes a halide, a nitrate or an acetylacetone compound of a metalselected from ruthenium, rhodium, palladium, osmium, iridium, platinumand the like, and a reducing agent; a catalyst system which includes ahalide or an acetylacetone compound of a metal selected from titanium,vanadium, zirconium, tungsten and molybdenum, and an organoaluminumcompound as a co-catalyst; a Schrock-type or Grubbs-type livingring-opening metathesis polymerization catalyst (JP-A-7-179575, J. Am.Chem. Soc., 1986, 108, p. 733, J. Am. Chem. Soc., 1993, 115, p. 9858,and J. Am. Chem. Soc., 1996, 118, p. 100); and the like.

These metathesis polymerization catalysts can be used either alone or incombination.

The amount of the metathesis polymerization catalyst to be used may beappropriately selected taking account of the polymerization conditionsand the like, but is normally 0.000001 to 0.1 mol, and preferably0.00001 to 0.01 mol based on 1 mol of the monomer.

A linear α-olefin having 4 to 40 carbon atoms such as 1-butene, 1-hexeneand 1-decene can be used as a molecular weight modifier when subjectingthe cycloolefin monomer to ring-opening polymerization.

The linear α-olefin is normally added in an amount of 0.001 to 0.030mol, preferably 0.003 to 0.020 mol, and more preferably 0.005 to 0.015mol based on 1 mol of the cycloolefin monomer.

The ring-opening polymerization of the cycloolefin monomer can beeffected in an organic solvent. The organic solvent is not particularlylimited as long as it is inert to the polymerization reaction. Examplesof the organic solvent include an aromatic hydrocarbon-based solventsuch as benzene, toluene and xylene; an aliphatic hydrocarbon-basedsolvent such as n-pentane, n-hexane and n-heptane; an alicyclichydrocarbon-based solvent such as cyclohexane, methylcyclohexane,decalin and bicyclononane; a halogenated hydrocarbon-based solvent suchas dichloroethane, chlorobenzene, dichlorobenzene and trichlorobenzene;and a mixed solvent which includes two or more of these solvents.

The polymerization temperature is not particularly limited, but isnormally −50 to 250° C., preferably −30 to 200° C., and more preferably−20 to 150° C. The polymerization time is appropriately selected takingaccount of the polymerization conditions, but is normally 30 minutes to20 hours, and preferably 1 to 10 hours.

A hydrogenated product of the ring-opening copolymer can be obtained bysubjecting the ring-opening copolymer obtained in accordance with theabove-described method to a hydrogenation reaction. The hydrogenationreaction of the ring-opening copolymer can be effected by bringing thering-opening copolymer into contact with hydrogen under the presence ofa hydrogenation catalyst in accordance with an ordinary method.Specifically, the hydrogenation reaction of the ring-opening copolymercan be effected in the same manner as the method described above in theexplanation of the copolymer (AI).

The glass transition temperature (Tg) of the copolymer (A) according toone embodiment of the invention is 100° C. or higher, preferably 115 to175° C., and more preferably 130 to 160° C. A copolymer having a glasstransition temperature (Tg) of 100° C. or higher is preferably used as aresin component of a resin formed article having excellent heatresistance.

The glass transition temperature (Tg) of the copolymer (A) can bemeasured by the method described in Examples.

The refractive index (n_(d)) of the copolymer (A) according to oneembodiment of the invention is 1.545 or higher, preferably 1.547 to1.700, and more preferably 1.548 to 1.600. A copolymer having arefractive index (n_(d)) of 1.545 or higher is preferably used as aresin component of an optical formed article.

The refractive index (n_(d)) of the copolymer can be measured by themethod described in Examples.

The Abbe's number of the copolymer (A) according to one embodiment ofthe invention is 50 or larger, preferably 53 to 60, and more preferably54 to 58.

The Abbe's number means a value indicating a degree of the refractiveindex for each wavelength of light (wavelength dispersion of refractiveindex). When the refractive indexes of the materials to lights of F line(wavelength: 486.1 nm), d line (wavelength: 587.6 nm) and Cline(wavelength: 656.3 nm) of the Fraunhofer lines are defined as n_(F),n_(d) and n_(c), respectively, the Abbe's number (ν_(d)) is defined bythe following equation (1).

ν_(d)=(n _(d)−1)/(n _(F) −n _(c))   (1)

The larger the Abbe's number (ν_(d)) of the material is, the lower thewavelength dispersion of the refractive index is and the lower theunevenness of the light emission angles for respective wavelengths is.The smaller the Abbe's number of the material is, the higher thewavelength dispersion of the refractive index is and the higher theunevenness of the light emission angles for respective wavelengths is.

A copolymer having an Abbe number (ν_(d)) of 50 or larger is preferablyused as a raw material for producing a low-dispersion optical member.

Normally, a glass transition temperature and a refractive index of anobtained copolymer tend to increase by introducing an aromatic ring intoits molecule, but an Abbe's number decreases. Thus, a copolymer having ahigh glass transition temperature (Tg), a high refractive index and ahigh Abbe's number is hardly obtained even by this method.

On the other hand, a copolymer having a high glass transitiontemperature (Tg), a high refractive index and a high Abbe's number canbe efficiently obtained by appropriately utilizing a cycloolefin monomerhaving a polycyclic structure such as deltacyclene or MMD like thecopolymer (A) according to one embodiment of the invention.

A birefringence (δn) per a unit thickness of the copolymer (A) accordingto one embodiment of the invention is preferably −100 to +100, morepreferably −85 to +80, and particularly preferably −60 to +60.

A birefringence per a unit thickness can be measured by the methoddescribed in Examples.

In relation to the copolymer (AI) according to one embodiment of theinvention, a copolymer having a higher glass transition temperature, ahigher refractive index and a higher Abbe's number can be easilyobtained by using a monomer having a large ratio of the number of carbonatoms to the number of hydrogen atoms such as deltacyclene and MMD as acycloolefin monomer, or by using a monomer having a ring structure as anacyclic olefin monomer.

Additionally, in relation to the copolymer (AII) according to oneembodiment of the invention, although a ring-opening copolymer tends tohave a lower glass transition temperature and a lower refractive indexthan those of an addition copolymer, a copolymer having a sufficientlyhigh glass transition temperature, a sufficiently high refractive indexand a sufficiently high Abbe's number can be easily obtained by using amonomer having a large ratio of the number of carbon atoms to the numberof hydrogen atoms such as deltacyclene and MMD as a monomer to be used.

2) Polymer (B)

The polymer (B) according to one embodiment of the invention is aring-opening homopolymer obtained by ring-opening polymerization of onlya monomer (MMD) represented by the following formula (I)

(hereinafter referred to as “polymer (α)” in some cases), a ring-openingcopolymer obtained by ring-opening copolymerization of an MMD and amonomer capable of ring-opening copolymerization with the MMD(hereinafter referred to as “polymer (β)” in some cases), or ahydrogenated product thereof (hereinafter referred to as “polymer (γ)”in some cases).

A polymer having excellent transparency, a high refractive index and alow birefringence can be obtained by using the MMD as a monomer.

The MMD can be synthesized by the reactions (α) and (β).

As mentioned above, the MMD includes 4 stereoisomers represented by thefollowing formulas.

In the present invention, all of these stereoisomers can be used asmonomers. Further, as a monomer, one isomer may be used alone, or anisomer mixture containing 4 isomers in an arbitrary ratio may be used.

Above all, for the monomer used for the present invention, a monomerhaving a lot of endo-endo products or the endo-exo products is preferredbecause of the birefringence (δn) per a unit thickness close to zero.The total amount of the endo-endo products and endo-exo products ispreferably 10 wt % or more, more preferably 30 wt % or more, even morepreferably 50 wt % or more, and particularly preferably 70 wt % or morebased on all monomers.

In the polymer (β) or the polymer (γ) (with the proviso that it is ahydrogenated product of the polymer (β)) (hereinafter they arecollectively referred to as “copolymer (C) according to one embodimentof the invention” in some cases), the monomer other than MMD is notparticularly limited as long as it is capable of ring-openingcopolymerization with MMD. Examples of the monomer other than MMDinclude a monocyclic cycloolefin monomer, a norbornene-based monomer (amonomer containing a norbornene ring), and the like.

Examples of the monocyclic cycloolefin monomer include a cyclicmonoolefin such as cyclobutene, cyclopentene, cyclohexene, cyclohepteneand cyclooctene, and a derivative thereof (a monomer having asubstituent on its ring, the same applies to the following); a cyclicdiolefin such as cyclohexadiene and cyclooctadiene, and a derivativethereof; and the like.

Examples of the norbornene-based monomer include a bicyclic monomer suchas bicyclo[2.2.1]hept-2-ene (trivial name: norbornene) and a derivativethereof; a tricyclic monomer such astricyclo[4.3.0.1^(2,5)]deca-3,7-diene (trivial name: dicyclopentadiene)and a derivative thereof; a tetracyclic monomer such as7,8-benzotricyclo[4.3.0.1^(2,5)]deca-3-ene (trivial name:methanotetrahydrofluorene, also referred to as“tetracyclo[7.4.0.0^(2,7).1^(10,13)]trideca-2,4,6,11-tetraene),tetracyclo[4.4.0.1^(2,5).1^(7,10)]dodeca-3-ene (trivial name:tetracyclododecene) and a derivative thereof; a monomer having not lessthan 5 rings such as 1,2,3,3a,4,6a-hexahydro-1,2,4-methenopentalene(trivial name: deltacyclene, hereinafter referred to as “DCL” in somecases) and a derivative thereof; and the like.

When these monomers have a substituent, the position of the substituentis not limited. Examples of the substituent include an alkyl group suchas a methyl group and an ethyl group; an alkenyl group such as a vinylgroup; an alkylidene group such as an ethylidene group and apropane-2-ylidene group; an aryl group such as a phenyl group; a hydroxygroup; an acid anhydride group; a carboxyl group; an alkoxycarbonylgroup such as a methoxycarbonyl group; and the like.

Among these monomers, the DCL [compound represented by the followingformula (II)] is preferred because a copolymer having a higherrefractive index and a lower birefringence can be easily obtained.

These monomers other than MMD can be used either alone or incombination.

In the copolymer (C) according to one embodiment of the invention ofthis patent application, the content of the repeating unit derived fromthe MMD is preferably 50 wt % or more, more preferably 70 wt % or more,and even more preferably 80 wt % or more based on the whole repeatingunit. When the content of the repeating unit derived from the MMD is 50wt % or more based on the whole repeating unit, a copolymer having ahigher refractive index and a lower birefringence can be easilyobtained.

The polymer (α) and the polymer (β) can be synthesized by ring-openingpolymerization of a corresponding monomer in accordance with a knownmethod using a metathesis polymerization catalyst.

The metathesis polymerization catalyst is not particularly limited. Aknown metathesis polymerization catalyst may be used. Examples of themetathesis polymerization catalyst include a catalyst system including ahalide, a nitrate or an acetylacetone compound of a metal selected fromruthenium, rhodium, palladium, osmium, iridium, platinum, and the like,and a reducing agent; a catalyst system including a halide or anacetylacetone compound of a metal selected from titanium, vanadium,zirconium, tungsten and molybdenum, and an organoaluminum compound as aco-catalyst; a Schrock-type or Grubbs-type living ring-openingmetathesis polymerization catalyst (JP-A-7-179575, J. Am. Chem. Soc.,1986, 108, p. 733, J. Am. Chem. Soc., 1993, 115, p. 9858, and J. Am.Chem. Soc., 1996, 118, p. 100); a catalyst system including a complexhaving a metal such as chromium, molybdenum and tungsten and an imidegroup-containing ligand; and the like.

These metathesis polymerization catalysts can be used either alone or incombination. The amount of the metathesis polymerization catalyst to beused may be appropriately selected taking account of the polymerizationconditions and the like, but is normally 0.000001 to 0.1 mol, andpreferably 0.00001 to 0.01 mol based on 1 mol of the whole monomer.

A linear α-olefin having 4 to 40 carbon atoms such as 1-butene, 1-hexeneand 1-decene can be used as a molecular weight modifier when carryingout ring-opening polymerization.

The linear α-olefin is normally added in an amount of 0.001 to 0.030mol, preferably 0.003 to 0.020 mol, and more preferably 0.005 to 0.015mol based on 1 mol of the whole monomer.

The ring-opening polymerization can be effected in an organic solvent.The organic solvent is not particularly limited as long as it is inertto the polymerization reaction. Examples of the organic solvent includean aromatic hydrocarbon-based solvent such as benzene, toluene andxylene; an aliphatic hydrocarbon-based solvent such as n-pentane,n-hexane and n-heptane; an alicyclic hydrocarbon-based solvent such ascyclohexane, methylcyclohexane, decalin and bicyclononane; a halogenatedhydrocarbon-based solvent such as dichloroethane, chlorobenzene,dichlorobenzene and trichlorobenzene; and the like.

The polymerization temperature is not particularly limited, but isnormally −50 to 250° C., preferably −30 to 200° C., and more preferably−20 to 150° C. The polymerization time is appropriately selected takingaccount of the polymerization conditions, but is normally 30 minutes to20 hours, and preferably 1 to 10 hours.

The polymer (α) or the polymer (β) obtained in accordance with theabove-described method is subjected to a hydrogenation reaction, so thata polymer (γ) corresponding them can be obtained, respectively.

This hydrogenation reaction can be effected by bringing the polymer (α)or the polymer (β) into contact with hydrogen under the presence of ahydrogenation catalyst in accordance with an ordinary method.

The hydrogenation catalyst may be a homogeneous catalyst or aheterogeneous catalyst.

Since a homogeneous catalyst is easily dispersed in a hydrogenationreaction solution, the amount of catalyst to be added can be reduced. Inaddition, since a homogeneous catalyst exhibits sufficient activity evenwhen the temperature and the pressure are not increased, decompositionor gelation of the polymer (α), the polymer (β) and the polymer (γ)hardly occurs. Therefore, a homogeneous catalyst is preferably used fromthe viewpoint of cost and the quality of the product.

On the other hand, since a heterogeneous catalyst exhibits particularlyexcellent activity at a high temperature under high pressure, thepolymer (α) or the polymer (β) can be hydrogenated within a short time.Moreover, a catalyst residue can be easily removed after completion ofthe hydrogenation reaction. Thus, the heterogeneous catalyst ispreferably used from the viewpoint of production efficiency.

Examples of the homogeneous catalyst include a Wilkinson's complex[chlorotris(triphenylphosphine)rhodium(I)]; a catalyst including acombination of a transition metal compound and an alkylmetal compound,such as combinations of cobalt acetate/triethylaluminum, nickelacetylacetonate/triisobutylaluminum, titanocenedichloride/n-butyllithium, zirconocene dichloride/sec-butyllithium,tetrabutoxytitanate/dimethylmagnesium and the like; and the like.

Examples of the heterogeneous catalyst include a catalyst in which ametal such as Ni, Pd, Pt, Ru and Rh is supported on a support.Particularly, when the amount of impurities in the resultinghydrogenated product is to be reduced, it is preferable to use anadsorbent such as alumina and diatomaceous earth as the support.

The hydrogenation reaction is normally effected in an organic solvent.The organic solvent is not particularly limited as long as it is inertto the hydrogenation reaction. A hydrocarbon-based solvent is normallyused as the organic solvent since a hydrocarbon-based solvent can easilydissolve the polymer (γ). Examples of the hydrocarbon-based solventinclude an aromatic hydrocarbon-based solvent such as benzene, tolueneand xylene; an aliphatic hydrocarbon-based solvent such as n-pentane,n-hexane and n-heptane; an alicyclic hydrocarbon-based solvent such ascyclohexane, methylcyclohexane, decalin and bicyclononane; and the like.

These organic solvents can be used either alone or in combination. Inaddition, a solvent used for a ring-opening polymerization reaction isnormally also suitable as a solvent for a hydrogenation reaction, andtherefore, after the hydrogenation catalyst is added to the ring-openingpolymerization reaction solution, it can be subjected to thehydrogenation reaction.

The hydrogenation reaction can be effected in accordance with anordinary method.

The hydrogenation ratio varies depending on the type of hydrogenationcatalyst, and the reaction temperature. Therefore, when the polymer (α)or the polymer (β) has an aromatic ring, a residual ratio of thearomatic ring can be controlled by selection of the hydrogenationcatalyst, adjustment of the reaction temperature or the like. Forexample, the unsaturated bonds of an aromatic ring can be allowed toremain to a certain extent or higher by controls such as selection of ahydrogenation catalyst, decrease of the reaction temperature, loweringof the hydrogen pressure and reduction of the reaction time.

A catalyst residue can be removed by a treatment such as centrifugationand filtration after completion of the hydrogenation reaction. Inaddition, a catalyst deactivation agent such as water and alcohol may beused, or an adsorbent such as activated clay and alumina may be added,as required.

The weight average molecular weight (Mw) of the polymer (B) according toone embodiment of the invention is preferably 10,000 to 300,000, andmore preferably 20,000 to 200,000, and particularly preferably 30,000 to150,000. If the weight average molecular weight (Mw) of the polymer istoo low, the strength of the resin formed article possibly decreases. Onthe other hand, if the weight average molecular weight (Mw) of thepolymer is too high, the formability of the forming material possiblydecreases.

The molecular weight distribution (Mw/Mn) of the polymer (B) is notparticularly limited, but is preferably 1 to 8, and more preferably 1 to6.

When the molecular weight distribution of the polymer (B) is within theabove range, a resin formed article having sufficient mechanicalstrength can be obtained.

The weight average molecular weight (Mw) and the number averagemolecular weight (Mn) of the polymer (B) refer to standardpolyisoprene-equivalent values determined by gel permeationchromatography (GPC) using cyclohexane as an eluent.

The polymer (B) according to one embodiment of the invention is apolymer having a high refractive index and a low birefringence becauseit has a repeating unit derived from the MMD.

The refractive index (n_(d)) of the polymer (B) according to oneembodiment of the invention at 25° C. is preferably 1.540 or higher, andmore preferably 1.545 to 1.560.

The birefringence (δn) per a unit thickness of the polymer (B) accordingto one embodiment of the invention is preferably −100 to +100, morepreferably −85 to +80, and particularly preferably −60 to +60.

The refractive index and the birefringence per a unit thickness can bemeasured in accordance with the method described in Examples.

In the polymer (B) according to one embodiment of the invention, amelting point may be observed depending on a state of a measurementsample, but when DSC measurement is carried out using a measurementsample obtained by melting and subsequent cooling, a melting point isnormally not observed. Thus, the polymer (B) according to one embodimentof the invention has an excellent transparency where respective polymerchains hardly align, even if the polymer chains have high-level tacticstructures.

The light transmittance of light having a wavelength of 650 nm in thesheet formed article with a thickness of 3 mm obtained by using thepolymer (B) according to one embodiment of the invention is preferably88% or higher, more preferably 90% or higher, and even more preferably92% or higher.

The glass transition temperature of the polymer (B) according to oneembodiment of the invention is preferably 120 to 180° C., and morepreferably 130 to 160° C.

When the glass transition temperature of the polymer (B) is within theabove range, the balance between the formability of the forming materialand the heat resistance of the resin formed article is improved.

In relation to the polymer (B) according to one embodiment of theinvention, the glass transition temperature of the syndiotactic polymertends to be within a range of 120 to 180° C. Thus, a polymer having adesired glass transition temperature can be efficiently obtained by apolymerization reaction using a known tungsten complex-based catalyst orthe like from which a syndiotactic polymer is obtained.

As described above, since the polymer (B) according to one embodiment ofthe invention has a repeating unit derived from the MMD, it exhibitsexcellent transparency, and furthermore a high refractive index and alow birefringence. As the polymer (B) according to one embodiment of theinvention, the polymer (γ) is preferred because of these superiorproperties, and the hydrogenated product of the polymer (α) or thehydrogenated product of the copolymer of the MMD and the DCL is morepreferred.

The polymer (B) according to one embodiment of the invention is usefulas a resin component for an optical formed article.

2) Forming Material

The forming material according to one embodiment of the inventioncontains the copolymer (A) or the polymer (B) according to oneembodiment of the invention. The forming material may contain a resincomponent other than the copolymer according to one embodiment of theinvention and other components such as an additive as long as theeffects according to one embodiment of the invention are not impaired.

Examples of the resin component other than the polymer according to oneembodiment of the invention (hereinafter referred to as “another resincomponent” in some cases) include styrene-based polymers such as astyrene/butadiene block copolymer, a styrene/butadiene/styrene blockcopolymer, a styrene/isoprene block copolymer, astyrene/isoprene/styrene block copolymer and a hydrogenated productthereof, and a styrene/butadiene random copolymer.

When the forming material according to one embodiment of the inventioncontains another resin component, its content is normally 0.1 to 100parts by weight, and preferably from 1 to 50 parts by weight based on100 parts by weight of the copolymer according to one embodiment of theinvention.

Examples of the additive include an antioxidant, a UV absorber, a lightstabilizer, a near-infrared absorber, a plasticizer, an antistaticagent, an acid scavenger and the like.

Examples of the antioxidant include a phenol-based antioxidant, aphosphorus-based antioxidant, a sulfur-based antioxidant and the like.

Examples of the phenol-based antioxidant include3,5-di-t-butyl-4-hydroxytoluene, dibutylhydroxytoluene,2,2′-methylenebis(6-t-butyl-4-methylphenol),4,4′-butylidenebis(3-t-butyl-3-methylphenol),4,4′-thiobis(6-t-butyl-3-methylphenol), α-tocopherol,2,2,4-trimethyl-6-hydroxy-7-t-butylchroman,tetrakis[methylene-3-(3′,5′-di-t-butyl-4′-hydroxyphenyl)propionate]methane, [pentaerythritoltetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate]], and the like.

Examples of the phosphorus-based antioxidant includedistearylpentaerythritol diphosphite,bis(2,4-di-t-butylphenyl)pentaerythritol diphosphite,tris(2,4-di-t-butylphenyl)phosphite,tetrakis(2,4-di-t-butylphenyl)-4,4′-biphenyl diphosphite, trinonylphenylphosphite, and the like.

Examples of the sulfur-based antioxidant include distearylthiodipropionate, dilauryl thiodipropionate and the like.

Examples of the UV absorber include a benzotriazole-based UV absorber, abenzoate-based UV absorber, a benzophenone-based UV absorber, anacrylate-based UV absorber, a metal complex-based UV absorber and thelike.

Examples of the light stabilizer include a hindered amine-based lightstabilizer.

Examples of the near-infrared absorber include a cyanine-basednear-infrared absorber; a pyrylium-based infrared absorber; asquarylium-based near-infrared absorber; a croconium-based infraredabsorber; an azulenium-based near-infrared absorber; aphthalocyanine-based near-infrared absorber; a dithiol metalcomplex-based near-infrared absorber; a naphthoquinone-basednear-infrared absorber; an anthraquinone-based near-infrared absorber;an indophenol-based near-infrared absorber; an azide-based near-infraredabsorber; and the like.

Examples of the plasticizer include a phosphoric acid triester-basedplasticizer, a fatty acid monobasic acid ester-based plasticizer, adihydric alcohol ester-based plasticizer, an oxy acid ester-basedplasticizer and the like.

Examples of the antistatic agent include a fatty acid ester of apolyhydric alcohol and the like.

Examples of the acid scavenger include magnesium oxide, zinc stearateand the like.

The contents of these additives can be appropriately determined takingaccount of the objects. The contents are normally 0.001 to 5 parts byweight, and preferably 0.01 to 1 part by weight based on 100 parts byweight of the copolymer according to one embodiment of the invention.

The forming material can be obtained by mixing each component inaccordance with an ordinary method. Examples of the mixing methodinclude a method of mixing each component in an appropriate solvent anda method of kneading the components in a molten state.

The components may be kneaded using a melt mixer such as a single-screwextruder, a twin-screw extruder, a Banbury mixer, a kneader and a feederruder. The kneading temperature is preferably 200 to 400° C., and morepreferably 240 to 350° C. The components maybe kneaded after adding eachcomponent at a time, or may be kneaded while adding the componentsstepwise.

After kneading, in accordance with an ordinary method, the resultingmixture is extruded in a shape of a rod, and cut using a strand cutterto have an appropriate length, so that it can be pelletized.

The forming material according to one embodiment of the inventioncontains the copolymer (A) or the polymer (B) according to oneembodiment of the invention.

A resin formed article having excellent heat resistance, a highrefractive index and a high Abbe's number can be obtained by using theforming material according to one embodiment of the invention containingthe copolymer (A). Thus, the forming material according to oneembodiment of the invention is suitably used as a forming material foran optical formed article such as a lens.

A resin formed article having excellent transparency and furthermore ahigh refractive index and a low birefringence can be efficientlyobtained by using the forming material according to one embodiment ofthe invention containing the polymer (B). Thus, the forming materialaccording to one embodiment of the invention is suitably used as aforming material for an optical formed article such as a lens.

In addition, the forming material containing the polymer (B) obtained bythe method of kneading in a molten state normally has superiortransparency where no melting point is observed by DSC measurement.

The forming material according to one embodiment of the invention issuitably used also for fuel application because of high density and highcombustion heat.

3) Resin Formed Article

The resin formed article according to one embodiment of the inventioncan be obtained by forming the forming material according to oneembodiment of the invention.

The forming method is not particularly limited. Examples of the formingmethod include injection forming, press forming, extrusion forming andthe like. Above all, injection forming is preferred because a desiredformed article can be precisely obtained, when the formed article is anoptical member or the like.

The melting temperature employed during forming differs depending on theforming material to be used, but is normally 200 to 400° C., andpreferably 210 to 350° C. When a die is used, the die temperature isnormally 20° C. to (Tg+15)° C., preferably (Tg−30)° C. to (Tg+10)° C.,and more preferably (Tg−20)° C. to (Tg+5) ° C., where the glasstransition temperature of the forming material is defined as Tg.

Since the resin formed article according to one embodiment of theinvention is obtained by forming the forming material according to oneembodiment of the invention, it has excellent heat resistance and a highrefractive index and a high Abbe's number.

The resin formed article according to one embodiment of the invention issuitably used as an optical member such as an optical lens, a prism, alight guide.

EXAMPLES

The present invention will be further described below by way of Examplesand Comparative Examples in detail. Note that the present invention isnot limited to the following examples. Hereinafter, the units “parts”and “%” respectively refer to “parts by weight” and “wt %” unlessotherwise indicated, and the pressure refers to a gage pressure.

The various properties were measured in accordance with the methoddescribed below.

(1) Molecular Weight

The weight average molecular weight (Mw) of the copolymer (A) or thepolymer (B) was measured as a standard polyisoprene-equivalent value bygel permeation chromatography (GPC) using cyclohexane as an eluent.

As the standard polyisoprene, a standard polyisoprene manufactured byTosoh Corporation (Mw=602, 1390, 3920, 8050, 13800, 22700, 58800, 71300,109000, 280000) was used.

The measurement was carried out using three columns (TSKgel G5000HXL,TSKgel G4000HXL and TSKgel G2000HXL) manufactured by Tosoh Corporationconnected in series, under conditions of a flow rate of 1.0 mL/minute, avolume of the injected sample of 100 μL and a column temperature of 40°C.

(2) Glass Transition Temperature

The glass transition temperature (Tg) of the copolymer (A) or thepolymer (B) was measured using a differential scanning calorimeter(product name: DSC6220SII, manufactured by NanoTechnology Inc.) at anincrease rate of 10° C./min, in accordance with JIS K 6911.

(3) Refractive Index

The copolymer (A) or the polymer (B) was formed into a sheet with athickness of 5 mm and left under an atmosphere at [glass transitiontemperature (Tg) of the addition copolymer−15]° C. for 20 hours toprepare a measurement sample.

For the resulting measurement sample, the refractive indexes (n_(d),n_(c), n_(F)) at 25° C. were measured using a precise refractometer(product name: KPR-200, light source=He lamp (587.6 nm), H2 lamp (656.3nm, 486.1 nm), manufactured by Shimadzu Corporation).

Table 1 shows refractive indexes of light having a wavelength of 587.6nm.

(4) Abbe's Number

The Abbe's number (ν_(d)) was calculated using the refractive indices(n_(d), n_(c), n_(F)) at 25° C. obtained by measurement of therefractive indices, in accordance with the following equation (1).

ν_(d)=(n _(d)−1)/(n _(F) −n _(c))   (1)

In the equation (1), n_(d), n_(c) and n_(F) represent refractive indicesat wavelengths of 587.6 nm, 656.3 nm and 486.1 nm, respectively.

(5) Birefringence (δn) Per Unit Thickness

The copolymer (A) or the polymer (B) was formed into a shape of 35 mm×10mm×1 mm. After fixing both ends of this sheet with clips, a 160 g weightwas fixed to one clip. Subsequently, in an oven at [glass transitiontemperature (Tg) of the copolymer−15]° C., the sheet was stretched whilethe sheet was suspended with the clip having no fixed weight as thestarting point for 10 minutes, to prepare a measurement sample.

For the resulting measurement sample, a retardation value of lighthaving a wavelength of 650 nm at the center part of the measurementsample was measured using a birefringence meter (product name:KOBRA-CCD/X, manufactured by Oji Scientific Instruments Co., Ltd.) (themeasured value is defined as “a”).

In addition, a thickness at the center part of the measurement samplewas measured (the measured value is defined as “b” (mm)) to determine aδn value in accordance with equation: δn=a×(1/b).

The closer the δn value is to zero, the lower the birefringence is. Inaddition, a sample with a birefringence generated in the stretchingdirection shows a positive value, and a sample with a birefringencegenerated in a direction perpendicular to the stretching direction showsa negative value.

(6) Analysis of Monomer (NMR)

A monomer was dissolved in deuterated chloroform (containing TMS) toprepare a measurement solution with a concentration of the monomer of5%. Using this solution, ¹H-NMR measurement was carried out at 40° C.

(Gas Chromatography)

The monomer was analyzed by gas chromatography (GC) under the followingconditions.

-   Sample solution: 5% cyclohexane solution-   Gas chromatographic analyzer: product name: 6850 series,    manufactured by Agilent Technologies, Inc.-   Column: product name: HP-1, 30 m, inner diameter: 0.32 mm, film    thickness: 25 μm, manufactured by Agilent Technologies, Inc.-   Split ratio: 70:1-   Split flow rate: 140 mL/min-   Injection temperature: 160° C.-   Injection volume: 1.0 μL-   Detection temperature: 250° C.-   Flow rate of N₂: 2.0 mL/min-   Temperature condition: holding at 40° C. for 6 minutes heating up to    240° C. at 10° C./min

(7) Melting Point

The melting point (Tm) of the polymer was measured using a differentialscanning calorimeter (product name: DSC6220SII, manufactured byNanoTechnology Inc.) at an increase rate of 10° C./min, in accordancewith JIS K 7121.

(8) Transparency

The resin composition was formed into a sheet having a thickness of 3 mmto prepare a measurement sample.

For the resulting measurement sample, the light transmittance (opticalpath length: 3 mm) of light having a wavelength of 650 nm was measuredusing an ultraviolet and visible spectrophotometer (product name: UV-VISV570, manufactured by JASCO Corporation) to evaluate the transparency ofthe resin sheet. Subsequently, the measurement sample was heated (at320° C. for 1 hour), and then the transparency of the heated resin sheetwas similarly evaluated.

The transparency was evaluated in accordance with the followingcriteria.

-   “Good”: the transmittance is 88% or higher.-   “Bad”: the transmittance is lower than 88%.

Production Example 1 Synthesis of Alcohol Compound (1)

Dicyclopentadiene (100 g) and 3-butene-1-ol (500 g) were added to astainless steel autoclave, the inside of the system was replaced bynitrogen, sealed, then heated to 220° C. while stirring the wholecontent, and reacted for 1 hour. Subsequently, dicyclopentadiene (100 g)was further added to the reaction solution, the inside of the system wasreplaced by nitrogen, sealed, and then the same reaction operation wasrepeated twice.

The reaction solution was transferred to an autoclave equipped with astirrer, to which 100 parts of cyclohexane and a diatomaceousearth-supported nickel catalyst (product name: T8400RL, nickel carryingratio: 58%, manufactured by Clariant) (0.5 g) were added. The inside ofthe autoclave was replaced by hydrogen, and then hydrogenation reactionwas carried out at 160° C. under a hydrogen pressure of 2.0 MPa for 2hours.

After completion of the hydrogenation reaction, the reactant waspressure-filtered at 0.25 MPa using a pressure filter (product name:Funda Filter, manufactured by IHI Corporation) with diatomaceous earth(product name: Radiolite (registered trademark) #500, manufactured bySHOWA CHEMICAL INDUSTRY CO., LTD.) as a filtration bed to obtain acolorless transparent solution. Cyclohexane in the resulting solutionwas distilled off using a rotary evaporator, and the residue wasdistilled under reduced pressure (113 to 116° C., 0.013 kPa) to obtain71 g of alcohol compound (1).

Production Example 2 Synthesis of Monomer (1)

60 g of the alcohol compound (1) and 200 g of diethyl ether were addedto a reactor whose inside had been replaced by nitrogen, into which 30 gof phosphorus tribromide was dropped while stirring the whole content atroom temperature for 1 hour. After completion of the dropping, stirringwas further continued for 23 hours to obtain a reaction solution. 400 gof toluene was added to the reaction solution, which was washed with 300mL of saturated sodium bicabonate aqueous solution three times, and thenthe organic layer was taken out by liquid separation.

Subsequently, while stirring the solution of the organic layer, 50 g ofpotassium t-butoxide was added to this solution at room temperature, andthe stirring was further continued for 5 hours to obtain a reactionsolution. 500 mL of toluene was added to the reaction solution, whichwas washed with 300 mL of 2 N hydrogen chloride aqueous solution threetimes, and then the organic layer was taken out by liquid separation.

Toluene in the organic layer was distilled off using a rotaryevaporator, and the residue was distilled under reduced pressure (80 to83° C., 0.13 kPa) to obtain 25 g of a monomer (1).

Production Example 3 Synthesis of Monomer (2)

750 mL of dichloromethane, 150 g of norbornadiene, 14.8 g of cobaltcatalyst [CoBr₂ (dppe)] and 23.5 g of zinc iodide were added to areactor whose inside had been replaced by nitrogen, and the wholecontent was stirred at 25° C. Acetylene gas was blown into the resultingsolution, to which 6.3 g of tetrabutylammonium borohydride was graduallyadded while stirring the whole content, and then the blowing ofacetylene gas and the stirring were continued for 2 hours. Subsequently,14.8 g of the cobalt catalyst was further added, and then the blowing ofacetylene gas and the stirring were continued for 2 hours.

200 g of silica gel was added to the reaction solution, stirred for 10minutes, and then impurities were filtered out. The filtrate wasdistilled off under reduced pressure to obtain 135 g of crude product.

The crude product was distilled under reduced pressure at 0.29 kPa at24° C. to obtain 90 g of monomer (2) [deltacyclene (DCL)]. As a resultof gas chromatography, the purity was 99%.

Production Example 4 Synthesis of Monomer (3) (MMD)

200 parts of norbornadiene and 30 parts of rhodium-active carbon (5% Rh)were added to a reactor whose inside had been replaced by argon, whichwas heated to 110° C. while stirring the whole content, and the reactionwas continued for 24 hours while maintaining the state.

After cooling the reaction solution, the solid content was filtered outto obtain 190 parts of crude product. The resulting crude product wasdistilled under reduced pressure (76° C., 80 Pa) to obtain 105 parts ofmonomer (3).

As a result of NMR measurement for the monomer (3), the monomer (3) wasan isomer mixture including an exo-endo product and an endo-endoproduct, and their ratio (exo-endo product:endo-endo product) wasestimated to be 86:14.

Example 1

A stirring bar, 30 mL of toluene, 174 mg of methylaluminoxane and 2 g ofmonomer (2) were put in a 100 mL autoclave whose inside had beenreplaced by nitrogen, to which a catalyst solution [1 mL of toluenesolution containing 0.25 μmol of t-BuCpTi(N═C(t-Bu)₂)Cl₂] was addedwhile stirring the whole content at 25° C. Immediately after adding thecatalyst solution, ethylene gas was introduced so that the pressure was0.2 MPa, to start addition polymerization reaction. The additionpolymerization reaction was continued for 10 minutes while maintainingthe temperature and the ethylene pressure in the autoclave. Afterdepressurization, the content in the autoclave was transferred into alarge amount of 2-propanol acidified by hydrochloric acid to precipitatea polymer. The resulting polymer (1) had a Tg of 166° C. and arefractive index of 1.553.

Example 2

A stirring bar, 8 g of toluene, 174 mg of methylaluminoxane, 1 g ofmonomer (1) and 1 g of monomer (2) were put in a 15 mL screw tube bottlewhose inside had been replaced by nitrogen, to which a catalyst solution[1 mL of toluene solution containing 5 μmol of CpTi(N═C(t-Bu)₂)Cl₂] wasfurther added to start addition polymerization reaction. The additionpolymerization reaction was carried out while stirring the whole contentat 25° C. for 120 hours, and then the content in the screw tube bottlewas transferred into a large amount of 2-propanol acidified byhydrochloric acid to precipitate a polymer. The resulting polymer (2)had a weight average molecular weight (Mw) of 19,000 and a molecularweight distribution (Mw/Mn) of 1.9. The polymer (2) had a Tg of 179° C.and a refractive index of 1.558.

Example 3

A stirring bar, 20 g of cyclohexane, 38.4 mg of 1-hexene, 2.5 g oftetracyclododecene (TCD) and 2.5 g of monomer (2) were put in a 100 mLampule bottle whose inside had been replaced by nitrogen, to which acatalyst solution [1 mL of toluene solution containing 6 μmol ofbenzylidene{1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene}dichloro(tricyclohexylphosphine) ruthenium] was further added, andthe whole content was stirred at 60° C. for 3 hours to carryoutring-opening polymerization reaction. The conversion ratio of themonomer into the polymer was 100%.

Subsequently, 25 g of the resulting polymerization solution and 200 g ofcyclohexane were transferred to an autoclave equipped with a stirrer,the inside of the autoclave was replaced by hydrogen, and thenhydrogenation reaction was carried out at 150° C. under a hydrogenpressure of 4.5 MPa for 6 hours. As a result of ¹H-NMR analysis, thehydrogenation ratio was 100%.

The resulting hydrogenation solution was dropped to a large amount of2-propanol to precipitate a polymer. The polymer was taken by suctionfiltration, and then vacuum-dried at 60° C. for 24 hours. The resultingpolymer (3) had a weight average molecular weight (Mw) of 16,000 and amolecular weight distribution (Mw/Mn) of 1.9. The polymer (3) had a Tgof 103° C. and a refractive index of 1.548.

Example 4

A stirring bar, 30 mL of toluene, 174 mg of methylaluminoxane and 2 g ofmonomer (3) were put in a 100 mL autoclave whose inside had beenreplaced by nitrogen, to which a catalyst solution [1 mL of toluenesolution containing 0.25 μmol of CpTi(N═C(t-Bu)₂)Cl₂] was added whilestirring the whole content at 25° C. Immediately after adding thecatalyst solution, ethylene gas was introduced so that the pressure was0.2 MPa, to start addition polymerization reaction. The additionpolymerization reaction was continued for 10 minutes while maintainingthe temperature and the ethylene pressure in the autoclave. Afterdepressurization, the content in the autoclave was transferred into alarge amount of 2-propanol acidified by hydrochloric acid to precipitatea polymer. The resulting polymer (4) had a weight average molecularweight (Mw) of 192,000 and a molecular weight distribution (Mw/Mn) of1.64. The polymer (4) had a Tg of 188° C. and a refractive index of1.552.

Comparative Example 1

A stirring bar, 30 mL of toluene, 174 mg of methylaluminoxane and 2 g ofTCD were put in a 100 mL autoclave whose inside had been replaced bynitrogen, to which a catalyst solution [1 mL of toluene solutioncontaining 0.25 μmol of [Me₂Si(η⁵-Me₄C₅)N(t-Bu)]TiCl₂ (CGC catalyst)]was added while stirring the whole content at 25° C. Immediately afteradding the catalyst solution, ethylene gas was introduced so that thepressure was 0.5 MPa, to start addition polymerization reaction. Theaddition polymerization reaction was continued for 10 minutes whilemaintaining the temperature and the ethylene pressure in the autoclave.After depressurization, the content in the autoclave was transferredinto a large amount of 2-propanol acidified by hydrochloric acid toprecipitate a polymer. The resulting polymer (5) had a Tg of 140° C. anda refractive index of 1.544.

Comparative Example 2

A stirring bar, 40 g of cyclohexane, 0.05 g of 1-hexene, 6.5 g ofmethanotetrahydrofluorene, 3.0g of tetracyclododecene and 0.5 g ofnorbornene were put in a 100 mL ampule bottle whose inside had beenreplaced by nitrogen, to which a catalyst solution [1 mL of toluenesolution containing 6 μmol ofbenzylidene{1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene}dichloro(tricyclohexylphosphine) ruthenium] was further added, andthe whole content was stirred at 60° C. for 3 hours to carryoutring-opening polymerization reaction. The conversion ratio of themonomer into the polymer was 100%.

Subsequently, 50 g of the obtained polymerization solution and 200 g ofcyclohexane were transferred to an autoclave equipped with a stirrer, towhich 0.5 g of diatomaceous earth-supported nickel catalyst (productname: T8400RL, nickel carrying ratio: 58%, manufactured b.JGC Catalystsand Chemicals Ltd.) was added. The inside of the autoclave was replacedby hydrogen, and then hydrogenation reaction was carried out at 190° C.under a hydrogen pressure of 4.5 MPa for 6 hours. As a result of ¹H-NMRanalysis, the hydrogenation ratio was 100%.

The diatomaceous earth-supported nickel catalyst in the hydrogenationsolution was taken by suction filtration, and the resulting polymersolution was dropped to a large amount of 2-propanol to precipitate apolymer. The polymer was taken by suction filtration, and thenvacuum-dried at 60° C. for 24 hours. The resulting polymer (6) had aweight average molecular weight (Mw) of 29,000 and a molecular weightdistribution (Mw/Mn) of 2.0. The polymer (6) had a Tg of 143° C. and arefractive index of 1.535.

TABLE 1 Comparative Comparative Example 1 Example 2 Example 3 Example 4Example 1 Example 2 Monomer α Ethylene Monomer (1) TCD Ethylene EthyleneNorbornene Monomer β Monomer (2) Monomer (2) Monomer (2) Monomer (3) TCDTCD Monomer γ — — — — — MTF Polymerization Addition AdditionRing-opening Addition Addition Ring-opening method polymerizationpolymerization polymerization polymerization polymerizationpolymerization Polymer 1 2 3 4 5 6 Tg 166° C. 179° C. 103° C. 189° C.140° C. 143° C. Refractive 1.553 1.558 1.548 1.552 1.544 1.535 indexAbbe's number 55 55 55 55 55 55 Birefringence 20 — 60 20 20 120 per aunit thickness (δn)

Table 1 shows the followings.

Although all of the copolymers of Examples 1, 2 and 4 and ComparativeExample 1 are addition polymers, the copolymers of Examples 1, 2 and 4have higher glass transition temperatures and higher refractive indexescompared to the copolymer of Comparative Example 1.

Although both the copolymers of Example 3 and Comparative Example 2 arering-opening polymers, the copolymer of Example 3 has a higherrefractive index compared to the copolymer of Comparative Example 2.

In addition, the copolymers of Examples have relatively lowbirefringence per a unit thickness and is excellent in lowbirefringence.

Production Example 5 Synthesis of DCL [Monomer (4)]

750 mL of dichloromethane, 150 g of norbornadiene, 14.8 g of cobaltcatalyst [CoBr₂ (dPPe)] and 23.5 g of zinc iodide were put in a reactorwhose inside had been replaced by nitrogen, and the whole content wasstirred at 25° C. Acetylene gas was blown into the resulting solution,to which 6.3 g of tetrabutylammonium borohydride was gradually addedwhile stirring the whole content, and then the blowing of the acetylenegas and the stirring were continued for 2 hours. Subsequently, 14.8 g ofthe cobalt catalyst was further added, and then the blowing of theacetylene gas and the stirring were continued for 2 hours.

200 g of silica gel was added to the reaction solution, stirred for 10minutes, and then insolubles were filtered out. The filtrate wasdistilled off under reduced pressure to obtain 135 g of crude product.

The crude product was distilled under reduced pressure at 0.3 kPa at 24°C. to obtain 90 g of monomer (4). As a result of gas chromatography, thepurity was 99%.

Production Example 6 Synthesis of MMD [Monomer (5)] by Reaction (α)

43 g of dicyclopentadiene and 250 g of monomer (4) were put in astainless steel autoclave, the inside of the system was replaced bynitrogen, then sealed, and heated to 220° C. while stirring the wholecontent, and the reaction was continued while maintaining the state for2 hour.

After cooling the reaction solution, 61 g of monomer (5) was obtained bydistillation under reduced pressure (57 to 61° C., 40 Pa). NMR charts ofthe monomer (5) are shown in FIGS. 1 and 2. Further, a GC chart of themonomer (5) is shown in FIG. 3.

As shown in the NMR chart of the monomer (5), the monomer (5) was anisomer mixture including an endo-exo product and an exo-endo product,and their ratio (endo-exo product:exo-endo product) was estimated to be97:3 (The isomer was identified with reference to J. Am. Chem. Soc.1972, 94, 5446. The above description also applies to Production Example6.).

Production Example 7 Synthesis of MMD [Monomer (6)] by Reaction (β)

200 parts of norbornadiene and 30 parts of rhodium-active carbon (5% Rh)were added to a reactor whose inside had been replaced by argon, whichwas heated to 110° C. while stirring the whole content, and the reactionwas continued for 24 hours while maintaining the state.

After cooling the reaction solution, the solid content was filtered outto obtain 190 parts of crude product. The resulting crude product wasdistilled under reduced pressure (76° C., 80 Pa) to obtain 105 parts ofmonomer (6). NMR charts of the monomer (6) are shown in FIGS. 4 and 5.Further, a gas chromatography (GC) chart of the monomer (6) is shown inFIG. 6.

As shown in the NMR chart of the monomer (6), the monomer (6) was anisomer mixture including an exo-endo product and an endo-endo product,and their ratio (exo-endo product:endo-endo product) was estimated to be86:14.

Monomers used in the following Examples and Comparative Examples areshown below.

-   Monomer (4): DCL-   Monomer (5): MMD [Reaction (A)]-   Monomer (6): MMD [Reaction (B)]-   MTF: Methanotetrahydrofluorene-   TCD: Tetracyclododecene-   NB: Norbornene

Example 5

2.0 parts of monomer (5) (1% based on the total amount of the monomersto be used for polymerization), 785 parts of dehydrated cyclohexane,15.0 parts of molecular weight modifier (1-hexene), 0.98 part ofn-hexane solution of diethylaluminum ethoxide (concentration: 19%), and11.7 parts of toluene solution of tungsten (phenylimido) tetrachloridetetrahydrofuran (concentration: 2.0%) (hereinafter referred to as “Wcatalyst (1)” in some cases) were put in a polymerization reactor whoseinside had been dried and replaced by nitrogen, which was stirred at 50°C. for 10 minutes.

Subsequently, 198.0 parts of the monomer (2) was continuously dropped tothe polymerization reactor for 150 minutes while maintaining the wholecontent at 50° C. and stirring. After completion of the dropping, thestirring was continued for 30 minutes, and then 4 parts of isopropylalcohol was added to terminate the polymerization reaction. As a resultof measuring the polymerization solution by gas chromatography, theconversion ratio of the monomer into the polymer was 100%, the polymerhad a weight average molecular weight (Mw) of 52,000 and a molecularweight distribution (Mw/Mn) of 2.9.

Subsequently, 300 parts of the resulting polymerization solution wastransferred to an autoclave equipped with a stirrer, to which 0.0043part of chlorohydridocarbonyltris (triphenylphosphine) ruthenium wasadded, and hydrogenation reaction was carried out at 160° C. under ahydrogen pressure of 4.5 MPa for 4 hours.

After completion of the hydrogenation reaction, the resulting solutionwas poured into a large amount of isopropanol to precipitate a polymer.The polymer was taken by filtration, to which 0.5 part of antioxidant[pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate](product name: “IRGANOX (Registered trademark) 1010” manufactured byBASF SE)] was subsequently added, which was put in an aluminum vat, anddried in a vacuum dryer (220° C., 133 Pa) for 6 hours to obtain apolymer (1).

The polymer (1) was slightly whitish. As a result of DSC measurement forthe polymer (1), the glass transition temperature (Tg) was 178° C., anda melting point (Tm) was observed at 299° C. When the polymer (1) wassubsequently heated at 320° C. under nitrogen atmosphere for 1 hour, nomelting point was observed by DSC measurement.

Various measurements were carried out for the polymer (1). The resultsare shown in Table 2.

Example 6

A polymer (2) was obtained in the same manner as Example 1 except that amonomer mixture (monomer (5):monomer (4)=9:1) was used instead of themonomer (5) and the amount of the molecular weight modifier (1-hexene)was 20.0 parts.

In the polymerization reaction, the conversion ratio of the monomer intothe polymer was 100%, and the weight average molecular weight (Mw) ofthe polymer before the hydrogenation reaction was 35,000, and themolecular weight distribution (Mw/Mn) was 3.4.

As a result of the DSC measurement for the polymer (2), no melting pointwas observed.

Various measurements were carried out for the polymer (2). The resultsare shown in Table 2.

Example 7

A polymer (3) was obtained in the same manner as Example 1 except thatthe monomer (6) was used instead of the monomer (5) and the amount ofthe molecular weight modifier (1-hexene) was 7.0 parts.

In the polymerization reaction, the conversion ratio of the monomer intothe polymer was 100%, and the weight average molecular weight (Mw) ofthe polymer before the hydrogenation reaction was 26,000, and themolecular weight distribution (Mw/Mn) was 4.0.

The polymer (3) was slightly whitish. As a result of DSC measurement forthe polymer (3), the glass transition temperature (Tg) was 143° C., anda melting point (Tm) was observed at 225° C. When the polymer (3) wassubsequently heated at 320° C. under nitrogen atmosphere for 1 hour, nomelting point was observed by DSC measurement.

Various measurements were carried out for the polymer (3). The resultsare shown in Table 2.

Example 8

0.05 part of polymerization catalyst[(1,3-dimesitylimidazolidine-2-ylidene) (tricyclohexylphosphine)benzylidene ruthenium dichloride] (hereinafter referred to as “Rucatalyst” in some cases), 100 parts of toluene, 20 parts of monomer (6)and 1.4 parts of molecular weight modifier (1-hexene) were added to aglass reactor whose inside had been replaced with nitrogen, and thewhole content was stirred at 60° C. for 1 hour to carry out thering-opening polymerization reaction. The conversion ratio of themonomer into the polymer was 100%, and the polymer had a weight averagemolecular weight (Mw) of 18,000 and a molecular weight distribution(Mw/Mn) of 1.5.

Subsequently, 300 parts of the resulting polymerization solution wastransferred to an autoclave equipped with a stirrer, to which 0.0043part of chlorohydridocarbonyltris (triphenylphosphine) ruthenium wasadded to carry out hydrogenation reaction at 160° C. under a hydrogenpressure of 4.5 MPa for 4 hours.

After completion of the hydrogenation reaction, the resulting solutionwas poured into a large amount of isopropanol to precipitate a polymer.The polymer was taken by filtration, to which 0.5 part of antioxidant[pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate](product name: “IRGANOX (registered trademark) 1010”, manufactured byBASF SE)] was subsequently added, which was put in an aluminum vat, anddried in a vacuum dryer (220° C., 133 Pa) for 6 hours to obtain apolymer (4).

The polymer (4) was slightly whitish. As a result of DSC measurement forthe polymer (4), the glass transition temperature (Tg) was 135.6° C.,and a melting point (Tm) was observed at 218° C. When the polymer (4)was subsequently heated at 320° C. under nitrogen atmosphere for 1 hour,no melting point was observed by DSC measurement.

Various measurements were carried out for the polymer (4). The resultsare shown in Table 2.

Comparative Example 3

7 parts of norbornene-based monomer mixture (MTF/TCD/NB=65/30/5) (1%based on the total amount of the monomers used for the polymerization),1,600 parts of dehydrated cyclohexane, 0.6 part of 1-hexene, 1.3 partsof diisopropylether, 0.33 part of isobutyl alcohol, and 0.84 part oftriisobutyl aluminum and 30 parts of cyclohexane solution containing0.66% of tungsten hexachloride (hereinafter referred to as “W catalyst(2)” in some cases) were put in a polymerization reactor dried andreplaced by nitrogen, which was stirred at 55° C. for 10 minutes.

Subsequently, 693 parts of the monomer mixture and 72 parts ofcyclohexane solution containing 0.77% of tungsten hexachloride werecontinuously dropped to the polymerization reactor for 150 minutes,respectively, while maintaining the reaction system at 55° C. andstirring. After completion of the dropping, the stirring was furthercontinued for 30 minutes, and then 1.0 part of isopropyl alcohol wasadded to terminate the polymerization reaction. As a result of measuringthe polymerization solution by gas chromatography, the conversion ratioof the monomer into the polymer was 100%, the polymer had a weightaverage molecular weight (Mw) of 24,000 and a molecular weightdistribution (Mw/Mn) of 2.2.

Subsequently, 300 parts of the resulting polymerization solution wastransferred to an autoclave equipped with a stirrer, to which 100 partsof cyclohexane and 2.0 parts of diatomaceous earth-supported nickelcatalyst (product name: “T8400RL”, nickel carrying ratio: 58%,manufactured b.JGC Catalysts and Chemicals Ltd.) were added. The insideof the autoclave was replaced by hydrogen, and then hydrogenationreaction was carried out at 180° C. under a hydrogen pressure of 4.5 MPafor 6 hours.

After completion of the hydrogenation reaction, the reactant waspressure-filtered at 0.25 MPa using a pressure filter (product name:“Funda Filter”, manufactured by IHI Corporation) with diatomaceous earth(product name: “Radiolite (registered trademark) #500” manufactured bySHOWA CHEMICAL INDUSTRY CO., LTD.) as a filtration bed to obtain acolorless transparent solution.

Subsequently, to the resulting solution, 0.5 part of antioxidant[pentaerythrityl-tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate](product name: “IRGANOX (registered trademark) 1010” manufactured byBASF SE)] was added based on 100 parts of the hydrogenated polymer.

This solution was filtered by a filter (product name: “Zeta Plus(registered trademark) 30H”, pore diameter: 0.5 to 1 μm, manufactured byCUNO Filter Systems), and then the filtrate was filtered with a metalfiber filter (pore diameter: 0.4 μm, manufactured by NICHIDAI CO., LTD.)to remove contaminants.

Subsequently, for the filtrate obtained above, cyclohexane and othervolatile components were removed from the solution at 260° C. and 1 kPaor lower using a cylindrical concentration dryer (manufactured byHitachi, Ltd.), and then the hydrogenated polymer was extruded in amolten strand state from a die directly connected to the concentrator,cooled with water, and then cut with a pelletizer (product name: “OSP-2”manufactured by OSADA SEISAKUSHO) to obtain a pellet of the hydrogenatedpolymer [polymer (5)].

Various measurements were carried out for the polymer (5). The resultsare shown in Table 2.

Comparative Example 4

Polymerization reaction was carried out in the same manner asComparative Example 1 except that MTF was used instead of thenorbornene-based monomer mixture. The resulting polymer had a weightaverage molecular weight (Mw) of 26,000 and a molecular weightdistribution (Mw/Mn) of 2.2. As a result of DSC measurement, no meltingpoint was observed in this polymer.

Subsequently, the resulting polymer was hydrogenated in the same manneras the hydrogenation reaction in Comparative Example 1 to obtain apellet of the hydrogenated polymer [polymer (6)].

Various measurements were carried out for the polymer (6). The resultsare shown in Table 2.

TABLE 2 Comparative Comparative Example 5 Example 6 Example 7 Example 8Example 3 Example 4 Ratio of MMD (Monomer 100 90 — — — — monomer (%)(6)) MMD (Monomer — — 100 100 — (5)) DCL (Monomer — 10 — — — (4)) MTF —— — — 65 100 TCD — — — — 35 — NB — — — — 5 — Catalyst for polymerizationW catalyst W catalyst W catalyst Ru W catalyst W catalyst reaction (1)(1) (1) catalyst (2) (2) Glass transition 178 163 143 135.6 149 160temperature Tg (° C.) Refractive index nd 1.549 1.550 1.550 1.550 1.53501.5345 Abbe's number vd 56 56 56 56 56 56 Birefringence per a unit 50 5080 80 120 110 thickness (δn) Transparency (before Bad Good Bad Bad GoodGood heating)

Table 2 shows the followings.

The polymers (1) to (4) of Examples 5 to 8 are polymers having highrefractive index and low birefringence. In addition, although polymers(1), (3) and (4) immediately after the synthesis are whitish andinferior in transparency, the transparency is improved by heattreatment.

On the other hand, the polymers (5) and (6) of Comparative Examples 3and 4 are excellent in transparency but their refractive indexes are nothigh, and they are inferior in low birefringence.

1. A copolymer (A); which is a copolymer obtained by copolymerizing oneor plural cycloolefin monomers and one or plural acyclic olefinmonomers, or a copolymer obtained by copolymerizing two or morecycloolefin monomers, wherein a glass transition temperature (Tg) is100° C. or higher, a refractive index is 1.545 or higher, and an Abbe'snumber is 50 or larger.
 2. The copolymer (A) according to claim 1,wherein a ratio of the number of carbon atoms to the number of hydrogenatoms (number of carbon atoms/number of hydrogen atoms) in at least oneof the cycloolefin monomers is 0.65 to 1.00.
 3. The copolymer (A)according to claim 1, wherein at least one of the cycloolefin monomersis a norbornene-based monomer.
 4. The copolymer (A) according to claim1, wherein at least one of the cycloolefin monomers is a deltacyclene.5. The copolymer (A) according to claim 1, wherein at least one of thecycloolefin monomers is a monomer represented by the following formula(I).


6. The copolymer (A) according to claim 1, wherein at least one of theacyclic olefin monomers is an α-olefin-based monomer having 2 to 18carbon atoms.
 7. The copolymer (A) according to claim 1, wherein atleast one of the acyclic olefin monomers is ethylene.
 8. A polymer (B)selected from: a ring-opening homopolymer obtained by ring-openingpolymerization of only a monomer represented by the following formula(I);

a ring-opening copolymer obtained by ring-opening copolymerization ofthe monomer represented by the above formula (I) and a monomer capableof ring-opening copolymerization with the monomer represented by theabove formula (I); a hydrogenated product of the ring-openinghomopolymer; and a hydrogenated product of the ring-opening copolymer.9. The polymer (B) according to claim 8, wherein the monomer capable ofring-opening copolymerization with the monomer represented by the aboveformula (I) is a compound represented by the following formula (II).


10. The polymer (B) according to claim 8, which is a polymer having arefractive index (nd) of 1.540 or higher.
 11. The polymer (B) accordingto claim 8, which is a polymer having a birefringence (δn) per a unitthickness of −100 to +100.
 12. The polymer (B) according to claim 8,wherein no melting point is observed, when a measurement sample obtainedby melting and subsequent cooling is subjected to DSC measurement whileheating it to 350° C. at an increase rate of 10° C./min.
 13. The polymer(B) according to claim 8, which is a polymer having a glass transitiontemperature of 120 to 180° C.
 14. A forming material containing thecopolymer (A) according to claim
 1. 15. The forming material accordingto claim 14, wherein no melting point is observed when carrying out DSCmeasurement.
 16. A resin formed article obtained by forming the formingmaterial according to claim
 14. 17. A forming material containing thepolymer (B) according to claim 8.